Replaceable tooth block for split wheel stump cutter

ABSTRACT

A stump grinding apparatus having a split cutting wheel includes several replaceable cutter blocks secured to the periphery of the wheel. One or more replacement teeth are removably anchored in holes in each block and may also be mounted on holes in the side of the split wheel as well. The teeth are typically provided with a hardened cutting face, and are reinforced with an extension projecting back from the face. Each tooth includes a shank which fits into one of the holes. The shank contains a groove which receives a spring clip or a spring pin for securing the tooth in the hole. The wheel periphery contains individual recesses that are shaped to receive the cutter blocks. Each block includes means for insuring alignment of the block in the corresponding recess. The block is wedged tightly into its recess to reduce the likelihood of accidental removal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of patent application Ser. No. 11/097,654filed Apr. 1, 2005, now U.S. Pat. No. 7,216,682 B1 which is a divisionof patent application Ser. No. 10/762,917, filed Jan. 22, 2004, now U.S.Pat. No. 6,877,535 B1 which is a division of patent application Ser. No.10/035,991, filed Dec. 31, 2001, now U.S. Pat. No. 6,698,477 B1.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of cutting wheels useful forgrinding tree stumps. More specifically, it relates to a stump cutterassembly and the component parts thereof

2. Description of the Related Art

It is known to provide a stump grinding apparatus to cut and dispose oftree stumps. The device finds use for agricultural applications, forproper lawn maintenance and care, and for site development. It is oftenrequired to lower a protruding stump to a level that is below grade sothat it will not interfere with plowing, disking and other farm tasks.For pleasing appearance of residential lawns, stumps of dead and fallentrees must likewise be cut away to a point that is below grade to allowfor soil to be placed there over for seeding or planting. When used forsite development, the apparatus permits soil to be moved as needed.

Typically, such a device includes a rotatable grinding wheel having aplurality of cuffing teeth disposed circumferentially about the wheel.The wheel can be powered by a chain drive, or by gear or belt, or may beat the end of a movable boom driven by a diesel or gasoline engine. Thecutting teeth of the stump grinders commonly encounter more than justwood when performing their tasks. They are brought into contact withrocks and all manner of buried debris, such as re-bar, wire, cinderblock and other materials of construction. Because of these hiddenobstacles, the teeth are subject to considerable wear and breakage, andthe peripheral surface of the cutting wheel experiences considerablewear as well.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a stump cutting wheel assembly. Theassembly comprises a wheel having a plurality of recesses spaced aroundthe circumference thereof. A replaceable cutter block is inserted intoeach recess and is secured to the wheel. The block has a leading surfaceand a trailing surface, two sides colinear with the sides of the wheel,a top with a radius of curvature corresponding to that of the cuttingwheel, and a bottom surface corresponding to the surfaces of the recess.A plurality of cutting teeth, each having a shank, is removably insertedinto holes in the cutter block and/or the sides of the wheel. Each shankhas a free end and an abutment end, the abutment end terminating in arearwardly extending shoulder that co-operates with the block to serveas a stop to limit linear and rotational movement of the shank in theblock or the wheel. An extension on the tooth projects rearwardly of thetooth face to rest against the adjacent surface of a block or the wheelto provide additional support for the tooth to resist shock and bendingmoments.

The cutting wheel is a split wheel having a first half and a second halfjoined to one other along the diametric surface thereof, each halfhaving a semicircular cut-out in the diametric surface to permit thewheel to be mounted around a hub keyed on a drive shaft. The two halvesof the wheel are joined together using clamping means comprising a pairof butterfly clamps. Each butterfly clamp fits in corresponding slots inboth halves of the wheel. The clamp engages a bolt extending from thesemicircular periphery along mating kerfs in the diametric surfaces.Preferably, the end of the kerfs immediately radially inward of theperiphery is enlarged to form a shoulder which receives a sleeve throughwhich the bolt passes.

Each cutter block includes means cooperating with a corresponding recessin the peripheral surface of the wheel to align the blocks with therotational direction of the wheel. The cooperating means includes a slotin the bottom of the recess, a corresponding slot in the bottom surfaceof the block and a key aligning the two slots. The back surface of eachrecess forms an undercut angle, and the trailing surface of the block isco-planar therewith. A hole extends through each block from the topsurface of the block to the bottom surface, and a threaded fastenersuch, as a bolt, passes through the hole for fastening the block intothe recess of the cutting wheel. The bolt is threaded into a nut platedisposed in a slot in the wheel radially beneath the block. A generallyV-shaped groove is formed between the front wall of the recess and theleading edge of the block, and a wedge is located between the two wallsof the groove, and is secured to said nut plate with a second threadedfastener. The shank on each tooth includes a circumferential groove, anda spring clip or a spring pin engages the groove to anchor the tooth ina corresponding hole in the block or in the wheel.

The invention further relates to a split wheel for a stump grinder. Thesplit wheel comprises a first half and a second half joined to oneanother along the diametric surfaces thereof. Each half has an axiallypositioned semicircular cut-out that allows the two halves to beassembled together. The two halves are assembled on a conventional hubusing a pair of clamps, such as butterfly clamps. A slot is locatedinboard of the semicircular periphery of each half and extends in fromeach mating plane to receive one clamp. A groove along the matingsurface joins each slot to the semicircular periphery to receive a boltextending in from the periphery and threaded into one of the clamps tohold the two halves together. The groove includes a shoulder recessedbeneath the peripheral surface to receive a sleeve which, in turn,receives the head of the bolt.

The split wheel further includes a plurality of recesses in theperiphery thereof, each recess shaped to receive a removable cutterblock. Each recess has a front edge, a bottom edge and a rear edge. Athreaded block fastener is located near the front edge. The rear edge isundercut to conform to the trailing surface of the block. Acircumferentially extending slot in the bottom of the recess is adaptedto receive an alignment key engageable with a corresponding slot in thebottom of each block. The threaded block fastener comprises a slotradially inwardly of each recess, and a nut plate in the slot having athreaded hole to receive the block fastener. The nut plate includes asecond threaded hole to receive a threaded fastener extending through ablock wedge. Each half of the wheel includes a semicircular cut-outalong the diametric surface on either side of the axially positionedcut-out, forming a non-axially located circular hole with thecorresponding cut-out in the other half. A conventional mounting hubcomprises two flanges bolted on either side of the wheel. A pair ofholes extends through the two flanges aligned with the two non-axialholes in the wheel, and drive pins extends through these holes in themounting hub. The mounting hub includes a keyway for mounting the wheelon the drive shaft.

The invention also relates to a replaceable cutter block adapted to beinserted into a recess in the periphery of the cutting wheel for a stumpgrinder. The cutter block has a top surface with a radius of curvaturecorresponding to the outer periphery of the cutting wheel. The blockalso includes a bottom surface that is co-planar with the bottom of therecess, two parallel side surfaces, a leading surface and a trailingsurface. The trailing surface corresponds to the rear surface of therecess. At least one hole in the block receives a removable cuttingtooth, the hole extending from the top surface or a side surface at anangle of inclination from the said surface toward the back surface of ablock. The hole extends into the block toward the trailing surface at anangle of between about 30° and about 60°. The block includes means, suchas a slotted key way adapted to receive a key extending longitudinallyalong the bottom thereof, to engage a corresponding alignment means inthe bottom of the recess. A threaded fastener secures the block into therecess of the cutting wheel. This fastener comprises a bolt adapted tobe threaded into a nut plate positioned in a slot within the cuttingwheel radially beneath the block. The trailing surface of the blockconforms to the rear wall of the recess and has an angle of less than90° but greater than about 60° with respect to the bottom of the block.

The invention further comprises a cutting tooth to be removably engagedwith a stump cutting wheel or a block on the circumference of such awheel. The tooth comprises a planar cutting surface adapted to form anangle generally orthogonal to a side or a top of said block when thetooth is engaged therewith. It also includes a shank to be inserted intoa corresponding hole in the block, said shank having a free end and anabutment end. The abutment end terminates in a shoulder formed at rightangles to the shank and adapted to cooperate with the block to serve asa stop to limit the linear and rotational movement of the shank into theblock. An extension projects rearwardly of the tooth face and is adaptedto rest against the planar side or top surface of a block when the toothis inserted into the block, said extension serving to provide a supportfor the tooth when in use. The shank typically includes acircumferentially extending groove and a spring clip engaging the groovefor the purpose of providing a compressive fit of the tooth in thecorresponding hole in a block. The shank forms an interior angle ofbetween about 30° and about 60°, preferably about 45°, with respect tothe cutting face of the tooth. The angle corresponds to the diagonalangle in the block or cutting wheel so as to provide the proper cuttingangle for the face when the tooth is properly mounted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the overall assembly of the presentinvention;

FIG. 2 is an enlarged, exploded view of the cutting wheel clamparrangement;

FIG. 3 is an assembled view of the arrangement of FIG. 2;

FIG. 4 is a partial exploded view of the wheel and cutter block;

FIG. 5 is an assembled view of the cutter block assembly of FIG. 4;

FIG. 6 is a view of the teeth of the present invention and theirrelationship to the cutting wheel; and

FIG. 7 is an exploded perspective view of the cutter block and teeth.

DETAILED DESCRIPTION OF THE INVENTION

The grinding wheel of the present invention is fabricated in two halvesthat are adapted to be held together by a butterfly type clamp. Thehalves are aligned in place by a wheel key which is held tight by a boltgoing through the middle of the wheel key and the wheel, to thebutterfly wheel clamp.

The grinding wheel also has removable wheel sections called blocks.These blocks are held in place in four ways. One, the wheel is machinedwith a cut-out specifically designed for the blocks to set into them.The wheel receives the block with the back and bottom face of the blockfitting into it. The space between the front face of the block and thewheel is designed for a wedge to set into it. Two, a safety bolt goesthrough the block to a common nut plate or a nut in the wheel. Three, awedge is set in between the wheel and front face of the block which isheld in place by a bolt that goes through the wedge and into the commonnut plate or nut in the wheel. Fourth, a key and keyway slips into theblock and wheel. This is called a block key.

The wheel and the block have holes machined into them. Some are for theteeth and some for the bolts. Each hole is machined into the wheel insuch a direction that, when the cutting tooth is inserted into it, thetooth will be at the appropriate angle for stump grinding. These holesare also machined to fit the design of the tooth in such a way that theyare prevented from rotating or moving in the hole when the wheel is inmotion.

The tooth has an extension on its top backside, which rests against thewheel or block. This gives support to the tooth and also keeps a toothfrom turning when in motion. The tooth has a shank that goes into thewheel hole or block hole. The shank has a spring clip on it, which holdsthe tooth in tight.

All the teeth can be easily removed from a backside of the wheel orblock. Teeth are removed with a punch and hammer. A block can be changedas needed by removing the wedge bolt and the block bolt.

Turning now to the drawings, FIG. 1 shows an exploded view of the stumpgrinder assembly 10 comprising a wheel 12, a plurality of cutter blocks14, and a plurality of cutting teeth 16 inserted in holes in the top andsides of the cutter block and the sides of the grinding wheel. The wheel12 is composed of two identical halves 12 a, 12 b joined to one anotherin the manner to be hereinafter described in greater detail inconnection with FIGS. 2 and 3.

Each half of the wheel has a mating surface 20 along the diameterthereof and a peripheral surface 22. The two mating surfaces include anaxially positioned semicircular cut-out 24 adapted to be mounted on ahub (not shown). A pair of smaller semicircular cut-outs 26 a, 26 b arelocated near the axial cut-out along the mating surfaces and are adaptedto receive a pair of conventional drive pins (not shown) extendingthrough flanges in the hub. Radially outwardly thereof are slots 28 a,28 b for receiving butterfly clamps 30 a, 30 b. A pair of bolts 32 a, 32b passes through annular wheel keys 34 a, 34 b to be threaded into theclamp. Grooves or kerfs 36 a, 36 b extend radially outwardly from theslots 28 a, 28 b to an enlarged opening 38 a, 38 b forming an abutmentshoulder 40 a, 40 b. The bolt 32 passes through the annular key 34 intothe clamp 30 and is tightened against the key, which abuts against theshoulder 40.

Turning now to FIGS. 4 and 5, the details of a removable cutter block 14and the manner in which it is fastened to the wheel is shown. The block14 includes a pair of parallel sides (one side 52 being shown), aleading surface 54, a trailing surface 56, a top surface 58 and a bottomsurface 60. The top surface 58 has a radius of curvature that matchesthat of the periphery of the wheel 12. A recess 62 is machined, etchedor molded into the periphery of the wheel, forming a front 64 and a rear66 separated by a base 68. The trailing edge 56 of the block 14 and therear 66 of the recess in the wheel 12 preferably form an identical anglewith respect to the bottom 60 of the block and the base 68 of the recessthat is less than 90°, preferably on the order of about 70°-85°. Theleading edge 54 of the block 14 and the front edge 64 of the recessdiverge, forming a V into which a wedge 70 is inserted and is secured inplace with a wedge bolt 72. The wedge bolt is threaded into a bolt plate74 or a nut (not shown) inserted into a slot 78 machined or otherwiseformed in the wheel 12 radially beneath the recess 62 and the block 14.A second bolt 80 holds the block in place, while the wedge forces theblock into tight engagement with the back edge of the recess.Circumferential alignment is maintained between the block 14 and therecess 62 by suitable means, such as an elongated slot 82 in the bottomof the block, a corresponding slot 84 in the base of the recess, and aslot key 86 engaging both slots.

One or more holes 88 are machined at an angle into the block 14 toreceive the cutting teeth 16. The holes include a circular portion 90that receives the shank of the tooth, and a generally square seat 92against which the shoulder of the tooth abuts. The circular portion ofthe mounting hole typically extends through to the opposite side of theblock 14 or the wheel 12 where it appears as an oval 18.

FIG. 6 shows two teeth 16 and a partial end view of the cutting wheel12. The wheel is intended to rotate in the direction shown by the arrow.Each tooth 16 includes a planar cutting face 100, a tooth body 102, acylindrical shank 104 having a free end 106 and an abutment end 108which forms a generally rectangular shoulder 110 where it intersects thebody 102 of the tooth. The shank 104 typically forms an angle betweenabout 30° and 60°, preferably about 45°, with respect to the cuttingface 100 of the tooth. The shank typically includes a groove 112, whichis engageable by a spring clip 114 or a spring pin 116 (shown in FIG.7). The tooth 16 includes an extension 118 projecting rearwardly fromthe tooth face 100. This extension includes a planar surface 120 thatrests against the side of the wheel 12 when the tooth shank 104 isinserted into a tooth hole 88.

FIG. 7 shows the cutter block 14 in a perspective view with two cuttingteeth 16 adapted to be inserted thereinto. Shown are the side 52, theleading edge 54, and the curved top 58 of the block. One hole 88 isshown in the top 58 and two holes are shown in the side 52 to receivethe teeth 16. Each of these holes includes a shoulder 92 and a roundportion 90 to receive the shank 104 of a tooth 16. A hole 94 extendsvertically through the block 14 to receive a block bolt (not shown) andincludes a shoulder 96 against which the head of the block bolt abuts.The tooth can be easily removed from a hole on the side of the block 14or the wheel 12 by tapping the free end 106 of the tooth shank 104 witha hammer and a punch. The teeth on the top of the block are held by aspring pin 116 pressed into and extending through a hole 50 in the sideof the block. These teeth can be easily disengaged from the block bydriving out the spring pin and then tapping the free end of the toothshank if it is accessible, or by prying it loose. The free end can beaccessed by machining a hole through the sides of the block tangentiallyto the free end of the shank so that the shank can be tapped out.

The tooth is typically fabricated by suitable means, such as forging orcasting. The face of the tooth preferably is made from a hard, impactresistant material, such as carbide steel brazed onto the body of thetooth.

As mentioned, the two halves of the wheel are assembled together arounda hub with the two mating surfaces joined together. The butterfly clamp30 is inserted into each of the slots 28, after which the bolt 32 isinserted through the key 34, and the groove 36 and is threaded into theclamp. When the two halves of the wheel are clamped together, aplurality of bolts is inserted into the holes 18 in the wheel andcorresponding holes on the two flanges of the hub. The two holes formedby the cut-outs 26 a and 26 b are aligned with corresponding holes inthe flanges. Drive pins are then inserted through the aligned holes sothat the wheel is driven by the rotation of the hub on the shaft of asuitable power source. Instead of using drive pins, other drive meansmay be used, such as slotted wheel halves mounted on a splined driveshaft.

Typically, the number and placement of teeth in the cutter block and inthe grinder wheel, as well as the angles and height of the cutting teethwith respect to the rotational direction of the cutting wheel, can bealtered in accordance with established practices. Furthermore, othermeans, such as cotter pins, can be used for anchoring the teeth in theholes in the blocks and the wheel. Likewise, the number of removablecutter blocks and corresponding recesses in the cutter wheel can beincreased or decreased depending on the overall size of the wheel andthe blocks. The recesses normally should be evenly spaced around theperiphery of the wheel for balance of the centrifugal forces duringoperation.

While the invention has been described in combination with embodimentsthereof, it is evident that many alternatives, modifications andvariations will be apparent to those skilled in the art in light of theforegoing teachings. Accordingly, the invention is intended to embraceall such alternatives, modifications and variations as fall within thespirit and scope of the appended claims. For example, the recesses andthe cutter blocks can be shaped so that the each block is secured to thewheel using a pair of block bolts front and back instead of using ablock wedge. Furthermore, the alignment of the blocks with the wheel canbe achieved by using a plurality of alignment pins instead of a key andslotted keyway.

The cutter blocks of the present invention can be used with other typesof cutter wheels such as solid wheels with improved results. Likewise,the blocks of the present invention can be mounted on unitary cuttingwheels, thereby enjoying the benefit and ease of replacing the blockswhen worn or broken.

1. A replaceable cutter block adapted to be inserted into a recess inthe periphery of the cutting wheel for a stump grinder, the cutter blockhaving a top surface with a radius of curvature corresponding to that ofthe cutting wheel, a bottom surface that is co-planar with the bottom ofthe recess, two parallel side surfaces, a leading surface and a trailingsurface, the trailing surface corresponding to the rear surface of therecess, and a least one hole to receive a removable cutting tooth, theat least one hole extending from the top surface or a side surface at anangle of inclination from the said top or side surface toward the backsurface of the block.
 2. The block according to claim 1 wherein aslotted key way on the bottom surface of the block is adapted to receivea key, wherein the key comprises an integral portion of the bottom ofthe recess, or separately engages a corresponding slot in the bottom ofthe recess.
 3. The block according to claim 1 further including athreaded fastener for fastening the block into the recess of the cuttingwheel.
 4. The block according to claim 3 wherein the threaded fastenercomprises a bolt adapted to be threaded into a nut plate positionedwithin the cutting wheel.
 5. The block according to claim 1 wherein thetrailing surface of the block conforms to the back wall of the recessand has an angle of less than 90° but greater than about 60° withrespect to the bottom of the block, said block further including alongitudinally extending key slot in the bottom thereof to receive a keyconforming to a key slot in the bottom of the recess to provide lateralstability of the block when secured in the recess of the cutting wheel.6. The block according to claim 4 further containing at least one holeextending into the block from a side thereof to receive a removablecutting tooth, the hole extending diagonally from the side thereoftoward the trailing surface thereof.
 7. The block according to claim 6wherein the at least one hole extends into the block toward the trailingsurface at an angle of between about 30° and about 60°.
 8. The blockaccording to claim 1 wherein said at least one hole includes a generallysquare seat, a shoulder and a circular portion.
 9. The block accordingto claim 4 wherein the threaded fastener comprises a block bolt.
 10. Theblock according to claim 9 including a hole extending vertically throughthe block from the top surface to the bottom surface to receive thebolt.